The field of the disclosure relates generally to automated fastener delivery equipment, and more specifically, to methods and apparatus for fastener staging in automated fastener delivery equipment.
In the production assembly of aircraft, the majority of substructure such as fuselage frames and longerons, along with wing spars and ribs, are joined to the skin of the aircraft with thousands of fasteners. Further, a plurality of fastener types, along with variations in diameters and grip lengths, are typically used in an aircraft assembly or subassembly. Generally, a fastener grip length refers to the cumulative thickness of the parts that the fastener holds together.
Automated fastener delivery systems that automatically deliver fasteners to a workpiece, or a fastening device, have been employed in various ways to simplify the fastener retrieval process in various types of automated fastener installation systems. Some of these known automated fastener delivery systems involve various types of storage devices and vibratory feed bowls that utilize different types of escapements for feeding fasteners through a tube to different types of fastening devices. Such known fastener delivery systems are typically employed in high rate production environments that have relatively large assembly systems permanently installed at a fixed location within a production facility. The equipment generally comprises a storage device for the fasteners and a mechanism or system that retrieves fasteners from the storage device and transports the fasteners to the workpiece or fastening device.
In at least one known fastener delivery system, fastener storage cassettes are utilized to cache the fasteners before delivery to a fastener installation device or the like with pressurized air. Typically, the fastener cassettes comprise at least one tube in which the fasteners are stacked longitudinally end to end. The fastener cartridges are filled off line either by hand or automatically. The fastener delivery system may be connected to more than one fastener installation device and may be used by more than one operator. When a fastener is requested by an operator, the appropriate fastener is removed from the proper storage tube, transferred to a drop point, and delivered through a passageway connecting the drop point to that operator's location and/or fastener installation tool. An operator may have to wait for the requested fastener to be removed from the cassette, transferred to the drop point and delivered through the passageway. This wait may be extended if the fastener delivery system is already retrieving a fastener for another operator. Because some assembly procedures may require hundreds of fasteners for each operator, this delay in receiving a requested fastener may amount to a significant amount of time.
Accordingly, a need remains in the art for an automated fastener delivery system that delivers fasteners to at least one work station or tool in a timely manner.